Electromagnet.



ELECTROMAGNET. APPLICATION FILED 11.14.23. lsn.

D. W. MARTIN 6: R. F. THOMPSON.

Patented 15, 1918.

lnventoffls I Davl d W. Martin Robert'FThornps on,

by Their Attorneg.

UNITED STATES PATENT OFFICE.

DAVID W. MARTIN am) nommr r. .rnomrson, or SCHENECTADY, nnw Yonx, ASSIGN- ons 1 GENERAL ELECTRIC COMPANY, A CORPORATION or new YORK.

ELECTBOMAGNET.

Specification of Letters Patent. Patented J an. 15, 1918.

Application filed January 23, 1917. Serial No. 144,031.

To all whom it may concern:

Be it'known that we, DAVID W. MARTIN 'and ROBERT F. THOMPSON, citizens of the 7 ing of the movable member of the magnet due to-alternations in the circuit are prevented in a simple and efiicient manner.

It is Well known that alternating current magnets are open to the objection that the travel, chatters against the movable member, in cases where it enga es a stationary polepiece at the limit 0 1pole piece, by reason of the-"reduction in pu l on ,the memher as the voltage passes through zero. It has been found that if the movable member or core engages the stationary pole piece so that the parts are in contact throughout the engaging surfaces, the chattering will be greatly reduced, or may even disappear. In the case of a solenoid, for instance, if the moving core having a flat surface engages a fiat stationary pole piece so that the two fiat surfaces are in contact uniformly throughout the engaging area, the chattering will completely disappear, if. the alinement is sufficiently good and the force. tending to separate the parts is not too great.

It has'heretofore been proposed to have one of the surfaces movable or yielding so that when the two members'engage they will aline themselves. generally involve the use of a spring and are mechanically and otherwise objectionable for reasons which-will be readily understood.

One of the objects of'our invention'is to provide means whereby the moving core orarmature and the/stationary pole piece aline themselves automatically upon engagement and the alinement is thereafter maintained.

In one form of our invention we have one its Such arrangements and weight w of the engaging surfaces, as for instance, the stat onary surface, movable inany plane so that it can properly aline itself with the moving surface when the two surfaces on gage and we provide means whereby the alining surfaces may then boss-cured in an alinement position so that thereafter the surfaces will always be in proper alinement.

In the accompanying drawing illustrating one form of our invention Figure 1 is a side elevation partly in section of a no-voltage -trip mechanism embodying our improvement; Fig. 2 is a detail of the self-alining pole-piece, and Fig. 3 is a diagram showing the connections and the switch mechanism in outline.

Referring to the drawings, it will be seen that we'have shown our invention in connection with a low voltage trip mechanism of well known design, but it is in no sense limited to use in this particular application. In Fig. 1, therefore, represents the winding for the switch which in this case is a no voltage winding connected across an A. G. supply'circuit as shown in Fig. 3; 11 is the core of the solenoid which is shown as being of solid iron and 12 thepole-piece which the'core engages at the limit of its movement. Trip lever 13 is pivoted at ll and is operated by a spring 15 connected ,to the magnet frame at 16 to trip the switch locking mechanisml? when released. The tripping lever is also weighted by means of the weight 17 pivoted to the lever at 18. The tripping lever is latched in its inoperative position shown in Fig. 1 by a bell crank lever 19 pivoted at 20. One end of the bell crank lever is pivoted to the core 11 by a slotted connection at 21, while the other end of the lever is provided with a roller 22 which engages'the end of the trip lever 13 and holds it against the action of the sprin I en the magnet is energize All of this mechanism is well known and forms no part of our invention.

The upper end of the plunger: 11, which is cylindrical in form, is fiat and enga es in flat surface of the pole piece 12. It has found in practice that if these two flat surfaces engage each other so as to make uniform contact throughout the surfaces, that the chattering due to alternating current in the winding 10 disappears. It is difiicult, however, to get the two parts to aline themselves so that the surfaces will be in uniform engagement. In order to insure that these two flat surfaces will engage with a uniform contact, We have provided the universal joint arrangement shown in Fig. 2. The main body of the pole piece'23 is threaded into the magnet frame as shown in Fig. l. The ortion' of .the pole piece which is enga e by the core is separate from the main ody but is mounted thereon for universal movement so that it may move freely in any plane and assume any position forced upon it by the fiat surface of the plunger 11. This movable member 24 has a fiat enga 'ng surface 25 and a shank 26 extending t rough the main body of the pole piece. The portion having a flat surface has a spherical concave surface 011 its inner side to conform to the spherical convex sure face 27 of the main body of the pole piece upon which it bears. The hole in the main body through which the shank 26 passes is considerably larger than the shank so as to permit free movement of the shank and a Washer 28 having a spherical concave bearing surface conforming to the spherical convex surface upon the main body of the pole piece is held in place by nuts 29. The shank also has plenty of clearance from this washer. a

As thus constructed, it will be seen that when the core 11 is first drawn upward into the solenoid, its upper face engages the flat face 2410f the movable portion of the pole piece, the. nuts 29 being slacked off so as to permit free movement of the movable member and 'the Washer. thus aline itself accurately. with the flat surface of the core. When the parts have alined themselves, the nuts 29 are taken up. and the movable member secured in the alined position. This arrangement has been. found very successful in bringing about this proper alinement' and obviates the necessity for machine Work after the parts are assembled. It has been found that when the alinement of the parts is accomplished the chattering of the plunger entirely disappears.

While we have described our invention as embodied in concrete form and as operating in a Specific manner in accordance with the provisions of the patent statutes, it should be understood that We do not limit our invention thereto, since various modifications thereof will suggest themselves to those skilled. in the art Without departing from the spirit of our invention, the scone of which :is set forth in the annexed claims.

The surface 25 will What we claim as new and desire to secure by Letters Patent of the United States, is 1-- 1. An electromagnet comprising a magnet winding, an armature movable thereby, a pole piece engaged by the armature at'the limit of its travel, means for causing alinement of these parts means for maintaining the alined condition after disengagement.

2. An electromagnetcomprising a magnet winding, an armature .movable thereby, a pole piece engaged by the armature at the limit of its travel, self-alining means associated with one of the engaging members and means for maintaining alinement after disengagement.

3. An electromagnet comprising a magnet winding, an armature movable thereby, a Self-alining stop engaged by the armature and means for locking the stop in place after it has alined itself.

4-. An electromagnet comprising a magnet winding, an armature movable thereby and having a flat engaging surface, a stop having a similar surface engaged by said arma ture at the limit of its travel and movable by such engagement so that the flat surfaces aline and means for locking the stop in its alined position.

5. An electromagnet comprising a sole-- noid, a core movable therein, a pole. piece engaged by the core at the limit of its travel, means for causing the engaging surfaces to aline upon engagement and means for maintaining alined conditions after disengagement.

6. .An electromagnet comprising a magnet Winding, an armature movable thereby and having a flat engaging surface, a flat ole piece engaged b the armature at the limit of its travel, se f-alining means associated with one'of the engaging members for causing the two. flat surfaces to contact uni formly throughout the engaging area, and

means for maintaining the alined position after disengagement.

7. An electromagnet comprising a magnet Winding, an armature movable thereby and having a flat engaging surface, apole piece having a flat engaging member mounted thereon for universal movement so as to insure uniform contact wlth the armature, and means for locking the member iu-the position which it assumes upon engagement.

8. An electromagnet comprising a magnet winding, an a rmature movable thereby, a

pole piece engaged bythe armature at the limit of its travel,-. a. self-alining universal joint associated with one of the engaging members, and, means for securing the uni'- upon engagement and versal joint in place after it has alined itself.

9. An 'electromagnetcomprising a magnet winding, an armature movable thereby and having a. flat engagi g surface,.a pole iece having a spherical donvex surfacei an an engaging member haviniaflatsurface, the place after it has alined itself with the said engaging member aving a spherical armature. n

concave surface adjustable on the spherical In witness whereof, We have hereun set 10 convex surface on the polepiece for causing our hands this 22nd day' of January, 19 7 5 a, self-alinement 0f the flat surfaces of the j armature and of the engaging member, and DAVID W. MARTIN.

J nean s for locking the engaglng member in ROBERT F. THOMPSON.

Gayle! 9! this patentn may be obtained for five cents each, by addressing the "Gommhsloner of Patuntl,

' Washington, D. g. 

